1. Field of the Invention
The present invention relates to agglomerates of latex particles formed by turning latex particles into regularly arranged and aggregated compacted grains by availing themselves of their flocculation and coagulation in polymer latex and, then, separating these grains from the polymer latex, after which their interior is further compacted.
2. Description of the Prior Art
Heretofore, as a method of recovering polymer from polymer latex obtained by emulsion or suspension polymerization, because the latex particles being in a dispersed phase very minute bodies, it is a normal practice to apply to process of refinement and drying, after forming aggregates of the latex particles. Generally, an aqueous solution of a coagulant such as inorganic salts, acids, etc., is added to latex or, conversely, latex is brought into aqueous solutio of such a coagulant, thereby to coagulatetthe latex in the liquid phase, and after turning it into a slurry form by such an operation as heat treatment, etc., it is obtained in a powder form through dehydration and drying. According to this method, the grain surface needs to be fused and solidified by way of heating treatment, since the coagulated grains themselves mainly comprise fine grains which are weak. Because the particle surface is fused and solidified, it becomes extremely difficult for foreign matters to move out of the grains, thus yielding high purity powders containin foreign matters. The powder has characteristics such that it has a small bulk density and low fluidity and tends to make dust and form block, and it is composed of grains which are amorphous, of which many are fine grains and which have a wide range of grain size distribution.
When this powder is ueed for the purpose of forming solutions or fine dispersions by redispersing it into solvents, since the latex particles have been fused by heating treatment, etc., they can not be adequately separated into latex particles; as a result, their dissolution is difficult and their perfect dispersion can not be formed; such other problems will arise. Moreover, degradation in quality due to containing of foreign matters is unavoidable. And when injection molding is to be performed, making direct use of this powder, reduction in the rate of injection or in the productivity occurs, or yellowing, silver streaks, flow marks, etc., will be generated, or degradation in physical properties will take place. Actually these problems make direct molding with it impossible.
Various powder manufacturing methods by way of coagulation have been developed with the aim at improvement in such characteristics, but they are intended mainly to solve problems in the processes for manufacturing powders or those involved in handling them, but are incapable of dealing with such themes as manufacturing large grains which adapt to the aforementioned two usage examples or removing of impruities, compacting of intragrain latex particles, etc. On the other hand, methods of drying latex without coagulation it, for example, spray drying or vacuum drying, are available, but all of them embrace problems which basically defy solution such as remaining of all impurities in latex, or in the forming of large grains, intragrain compacting, etc.